Infographic showing June 2011 Cesium-134 levels in the Pacific

Starting 375 miles off Japan, researchers on the Kaimikai o-Kanaloa measured radioisotope levels in various locations. They found that the Kuroshio Current blocked the southward flow of radioisotopes. Highest levels concentrated south of Fukushima, where currents trapped contamination in a swirling eddy. (Illustration by Jack Cook, © Woods Hole Oceanographic Institution)